The Village includes land in Plainfield and Wheatland townships. Part of Plainfield is located in Kendall County (Na-Au-Say and Oswego townships). With the growth in the Chicago suburbs in the 1990s and 2000s, the village has seen a building boom and a rapid population increase, from 4,500 in 1990 to 13,000 in 2000 to over 37,000 in 2007. Based on estimates created by the village and state government, Plainfield's population could grow as large as 120,000 by 2030. The Village is the fastest growing in the county.
The Village has established a community Preservation Commission and historic preservation ordinance. It is the home of the Lake Renwick Preserve, a county forest preserve used for birdwatching and other activities.
As of the census of 2000, there were 13,038 people, 4,315 households, and 3,521 families residing in the village. According to a 2003 special census, the village has a population of 20,673. The population density was 1,122.8 people per square mile (433.6/km²). There were 4,609 housing units at an average density of 396.9/sq mi (153.3/km²). The racial makeup of the village was 95.85% White, 0.84% African American, 0.08% Native American, 1.25% Asian, 0.01% Pacific Islander, 1.01% from other races, and 0.96% from two or more races. Hispanic or Latino of any race were 3.87% of the population.
There were 4,315 households out of which 47.3% had children under the age of 18 living with them, 73.6% were married couples living together, 5.7% had a female householder with no husband present, and 18.4% were non-families. 14.8% of all households were made up of individuals and 4.2% had someone living alone who was 65 years of age or older. The average household size was 3.01 and the average family size was 3.37.
In the village the population was spread out with 31.9% under the age of 18, 6.3% from 18 to 24, 36.2% from 25 to 44, 19.4% from 45 to 64, and 6.3% who were 65 years of age or older. The median age was 33 years. For every 100 females there were 100.6 males. For every 100 females age 18 and over, there were 96.7 males.
According to a 2007 estimate, the median income for a household in the village was $73,217, and the median income for a family was $81247. Males had a median income of $59,328 versus $35,861 for females. The per capita income for the village was $28,242. About 1.0% of families and 1.8% of the population were below the poverty line, including 2.2% of those under age 18 and 2.3% of those age 65 or over.
A special census conducted in 2007 pegged the city's population at 37,334.